Nonmelanoma skin cancer (NMSC) represents the most common form of cancer in the human body. The method for diagnosing and treating NMSCs requires removal of a biopsy that is prepared and stained for analysis on a standard optical microscope. This process is painful for patients, introduces a substantial delay into the flow of care, and represents a considerable cost to healthcare ($6.5B/yr) due to the large number of unnecessary biopsies. Zebra Medical Technologies (ZMT) aims to address the need for a better method to diagnose NMSCs by creating a noninvasive imaging technology capable of displaying histology like images of skin cellular structure in real time. In this project, ZMT will construct a portable, skin-imaging microscope for human clinical studies (Aim 1), develop software for data acquisition, image processing, and improved user interface (Aim 2), and demonstrate in 5 human subjects with basal cell carcinoma (BCC) the ability to detect pathologic features of BCC (Aim 3). ZMT is the creator of the only commercially available fiber coupled multiphoton microscopy (MPM) system for in vivo imaging of skeletal muscle cellular structures and contractile dynamics, the Zebrascope, which has been sold to three universities and one hospital to date. ZMT will adapt and optimize technologies invented for the Zebrascope to specifically visualize cellular structures in skin. The ZMT team possesses expertise in miniaturizing optical systems, designing disposable optical probes with highly repeatable alignment, imaging deep into living tissue, and conducting human studies with MPM under IRB oversight. ZMT has already proven feasibility of this concept with a bench top prototype that successfully imaged subcellular structures in the epidermis and dermis in living human skin and in excised tumor samples. Success in this project will lead to a larger clinical study in Phase II. ZMT views NMSC as a natural first target for real time diagnosis that paves the way for applications in melanoma diagnosis followed by other epithelial cancers such as oral, esophageal, and cervical.